Date of Award

Fall 12-18-2020

Degree Type


Degree Name

Master of Science (MS)



First Advisor

Dr. W. Crawford Elliott

Second Advisor

Dr. Daniel M. Deocampo

Third Advisor

Dr. Hasan A. Babaie

Fourth Advisor

Dr. Brian A. Powell


The Clay Mineral Society SWy-2 Na-montmorillonite clay was reacted for 90 days with 15 mM K+ at 200°C, the temperature/solution conditions of deep geologic repository near-field regions. X-ray diffraction of alteration products indicated that a minor amount of interstratification occurred in the clay. Hydrothermally altered samples sorbed stable Eu and 237Np almost as effectively as the unaltered clay. Average Kd values were 1.79 × 102 kg/L – 2.37 × 105 kg/L (Euonto altered clay), 3.05 × 102 kg/L – 1.54 × 106 kg/L (237Np onto altered clay), 3.55 × 104 kg/L – 1.30 × 106 kg/L (Euonto unaltered clay), and 1.04 × 103 kg/L (237Np onto unaltered clay). Speciation models indicated that Eu(III) and Np(V) complexation was influenced by the presence of chloride and hydroxide, but the largest observed impact on Eu and Np(V) sorption was solution pH which altered the affinity of Eu and Np(V) for the mineral surface.

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